Liquid Silicone Rubber (LSR) Molding

Create flexible, durable, and temperature-resistant parts with our expert LSR molding service. We produce high-performance silicone components for the most demanding applications.

Get Your LSR Molding Quote

A medical probe with a soft-touch overmolded grip, similar to LSR applications

A High-Performance Thermoset Process

Liquid Silicone Rubber (LSR) molding is a specialized manufacturing process similar to plastic injection molding. However, it uses a high-purity, two-part platinum-cured silicone as the raw material. Unlike thermoplastics, which are melted and then cooled, LSR is a thermoset material that is heated to induce an irreversible chemical reaction (curing) that solidifies the part.

The process involves pumping the two liquid components (A and B) from separate containers into a mixer, where they are combined. The mixed liquid is then injected into a heated mold cavity. The heat of the mold initiates the curing process, and within seconds to minutes, the part is formed and can be ejected.

A shore hardness chart showing the range of durometers for silicone rubber

Why Choose Liquid Silicone Rubber?

LSR offers a unique combination of properties that make it an ideal choice for a wide range of applications.

Biocompatibility & Safety

LSR is hypoallergenic, non-toxic, and resistant to bacteria growth. Medical-grade LSR can be sterilized via autoclave, ETO, and other methods, making it perfect for skin-contact and healthcare applications.

Extreme Temperature Resistance

Silicone parts maintain their flexibility and mechanical properties over a very wide temperature range, typically from -60°C to +180°C, making them suitable for automotive and industrial environments.

Chemical Resistance & Durability

LSR is chemically inert and resistant to water, oxidation, and many chemicals. It also has excellent tear strength and a low compression set, meaning it returns to its original shape after being compressed.

Common Applications for LSR Molding

Medical Devices: Respiratory masks, flexible seals for housings, surgical instrument grips, and fluidic valves.
Automotive: Gaskets, O-rings, connector seals, and vibration dampeners for under-the-hood applications.
Consumer Electronics: Soft-touch buttons, waterproof seals for wearable devices, keyboard keypads, and protective covers.
Food & Beverage: Baking molds, infant products like bottle nipples, and seals for food storage containers.

Colorful consumer products, illustrating an application for LSR components

LSR Molding FAQ

What is the difference between LSR and TPE?

LSR is a thermoset silicone, while TPE (Thermoplastic Elastomer) is a thermoplastic. LSR generally offers superior performance in terms of temperature resistance, chemical resistance, and lower compression set. TPE is often more cost-effective and easier to process, especially for overmolding onto other thermoplastics.

Can you add color to LSR parts?

Yes. Color pigments can be added to the liquid silicone before it is injected into the mold, allowing for a wide range of custom colors. The natural color of most LSR grades is translucent white.

What durometer (hardness) silicones do you offer?

We offer a wide range of hardness levels on the Shore A scale, typically from a very soft 20A to a firm 80A. The most common durometers are between 40A and 60A.